During a daily routine cutting process, and if the operator is doing everything correctly, it is almost impossible to know how the torch will react in non-standard conditions. For example, how it reacts when the torch is overheated, or the nozzle gets blocked. Thermacut^® has come up with a solution to simulate these extreme conditions, and to provide testing of its EX-TRAFLAME^® oxy-fuel cutting torches according to the international standards.

A specially designed ISO test device by Thermacut^® is able to simulate extreme conditions such as a flash back initiation, or torch overheating. These tests, which are clearly specified by international directive, also help development engineers to propose innovations focused on improving the lifetime and resistance of torches.

The EX-TRAFLAME^® oxy-fuel torches are tested according to the international directive EN ISO 5172 specifying the requirements for testing torches for flame welding, heating, and metal cutting. The directive is valid for machine torches with a cutting range of up to 300 mm. The purpose of the test is to prove the durability of the torch against constant flash back.

TORCH RESISTANCE AGAINST OVERHEATING

The torch is most exposed to high temperatures while piercing the metal sheet. The torch stands at the same position and the heat from a flame (reaching approximately 3000 °C with Acetylene) is heating the nozzle and torch body. Depending on the material thickness, the standard preheating time is approximately 1 minute. There are known cases when an operator is exceeding the preheating time too much, which causes damage to the torch. Simulation of the torch overheating helps us to know how the torch will react in this extreme situation and how resistant it is to rough handling. At the same time, it gives us valuable feedback and an opportunity to innovate the torch design further to reach the best cutting results.

During the test, the torch is lit inside a metal basin that is submerged in a medium-sized container filled with water. The heat is reflected from the walls of the metal basin to reinforce heating the torch. The above-mentioned directive specifies that the nozzle must be exposed to the back heat from a standard (neutral) flame for 3 minutes. During that time no flash back can appear.

BLOCKED NOZZLE ORIFICE

Testing the torch resistance in the situation when the nozzle orifice gets blocked simulates the two most frequent mistakes while cutting. The first one is the torch hitting the metal sheet, caused either by an operator´s mistake or by a failure of the Torch Height Control. The second mistake is an incorrectly made pierce caused by too slow torch speed, or even no torch speed, and afterward the melted material blocks the nozzle. Such mistakes lead to the flash backs into the torch body and cause damage.

A rotating pedestal is installed on the test rig and a sample of the copper material is then placed on the pedestal. There are five grooves on the material surface. The front surface of the nozzle is brought into sliding contact with the segment. The test directive specifies 30 interruptions of the flame in total. The torch test shall be considered satisfactory if there is no sustained flash back during five complete rotations. In the event of a sustained flash back, the test must be stopped immediately!

Check out the video showing the torch passing the tests
(slow motion picture)

While performing ordinary cutting, when the operator is doing everything correctly, it is difficult to know how the torch behaves when exposed to extreme conditions. That was the main reason why Thermacut has come up with a solution to simulate these conditions, and more. Based on these test results, development engineers can propose torch design enhancements to improve the durability of the EX-TRAFLAME^® torches. It is necessary to mention that during the tests no material is cut. So, these tests save money, time, and protect the health of the staff. The other benefit is a high variety of test condition settings, such as a time extension, adding device rotations etc. The Thermacut^® torches are tested properly. So, the customers can be sure that the EX-TRAFLAME^® torches are durable, reliable, and completely safe.

For more information about the EX-TRAFLAME^® oxy-fuel cutting torches and other products, please see our website www.ex-traflame.com.

Was the article interesting for you? For more information please do not hesitate to contact us at the following email: support@thermacut.cz

Text:               Thermacut, k.s.
Photos:           archive of Thermacut, k. s.